Conventionally, as plural braiding yarns in a braided gland packing, for example, known are braiding yarns which are disclosed in, for example, Japanese Patent Publication No. 6-27546 and Japanese Patent Application Laying-Open No. 6-74346. In each of the braiding yarns, an expanded graphite tape is bent so as to contract in the width direction, the whole outer periphery of the bent expanded graphite tape is covered by a reinforcing member configured by a knitted body or a braided body.
An expanded graphite tape is easily affected by tension or torsion. In a braiding yarn of a gland packing, therefore, cracks (breaks) sometimes unwillingly occur in end portions in the width direction of an expanded graphite tape. As such cracks are larger in number and in size, and as the number of braiding yarns in which such cracks occur is larger, the sealing performance of the gland packing is further impaired.
Even in the case where such cracks do not exist immediately after the production of a gland packing, cracks sometimes occur when, after the production, the gland packing is compression-molded to a predetermined size or into an annular shape. In the case where a gland packing is set to an apparatus so as to function as a seal, when a large fastening force is applied to the packing, such cracks may occur. When such cracks occur immediately after the production of a gland packing, a situation that the cracks are expanded by the compression molding or the fastening force is of course caused.
Therefore, it is an object of the invention to provide a gland packing in which impairment of the sealing performance due to such cracks that unwillingly occur can be suppressed.